How do I count columns in a table

Question

For example :

id | name  | age | gender 
----------------------------
1  | John  |  15 |  Male
2  | Maria |  18 |  Female
3  | Steph |  19 |  Female
4  | Jay   |  21 |  Male

How can I count the columns of this table using mysql?

Kyoko

Answer 1

SELECT count(*)
FROM information_schema.columns
WHERE table_name = 'tbl_ifo'

Trample

@codeMan 's point is very necessary. If you have multiple DBs with same table name then his point is must. – Healthy

Answer 2

I think you need also to specify the name of the database:

SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = 'SchemaNameHere'
  AND table_name = 'TableNameHere'

if you don't specify the name of your database, chances are it will count all columns as long as it matches the name of your table. For example, you have two database: DBaseA and DbaseB, In DBaseA, it has two tables: TabA(3 fields), TabB(4 fields). And in DBaseB, it has again two tables: TabA(4 fields), TabC(4 fields).

if you run this query:

SELECT count(*)
FROM information_schema.columns
WHERE table_name = 'TabA'

it will return 7 because there are two tables named TabA. But by adding another condition table_schema = 'SchemaNameHere':

SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = 'DBaseA'
  AND table_name = 'TabA'

then it will only return 3.

Asymmetry

I think your 'DatabaseNameHere' should be replaced with 'SchemaNameHere' – Permanent

Adding database name will provide more accurate results if you're running this in an environment where you might have multiple of the same app installed, thus multiple X tables are in the schema. – Lying

Answer 3

$cs = mysql_query("describe tbl_info");
$column_count = mysql_num_rows($cs);

Or just:

$column_count = mysql_num_rows(mysql_query("describe tbl_info"));

Substratum

this is very clever and flexible – Leinster

Answer 4

To count the columns of your table precisely, you can get form information_schema.columns with passing your desired Database(Schema) Name and Table Name.

Reference the following Code:

SELECT count(*)
FROM information_schema.columns
WHERE table_schema = 'myDB'  
AND table_name = 'table1';

Voncile

your answer is just the same as johntotetwoo – Kyoko

yes, because i can't submit my answer due to my connection. but after my submit, there are two answers and one is accepted already :D – Voncile

Answer 5

I have a more general answer; but I believe it is useful for counting the columns for all tables in a DB:

SELECT table_name, count(*)
FROM information_schema.columns
GROUP BY table_name;

Freemanfreemartin

Answer 6

Simply use mysql_fetch_assoc and count the array using count() function

Aguedaaguero

Answer 7

this query may help you

SELECT COUNT(COLUMN_NAME) FROM INFORMATION_SCHEMA.COLUMNS WHERE 
TABLE_CATALOG = 'database' AND TABLE_SCHEMA = 'dbo'
AND TABLE_NAME = 'tbl_ifo'

Imperious

Answer 8

I think you want to know the total entries count in a table! For that use this code..

SELECT count( * ) as Total_Entries FROM tbl_ifo;

Serried

This tells you how many ROWS not how many COLUMNS ... – Peppercorn